1. Field of the Invention
This invention relates generally to gas turbine engine rotors having air cooled turbine blades and, more particulary, to end seals at the turbine blade bases.
2. Description of the Prior Art
With more emphasis on fuel economy and more extensive use of air cooled turbine blades, minimizing the loss of cooling air from blade delivery circuits is an important design consideration. One very difficult area to seal is the turbine blade-turbine wheel attachment interface. Typically, cooling air is delivered into a clearance slot or manifold in the wheel inboard of the individual blade attachments from which it flows into the blade internal cooling cavities. The typical fir tree attachment on the blade base fits snugly into the wheel lugs and under centrifugal loading seals tightly against leakage. However, due to manufacturing tolerances the axial length of the blade base and wheel may differ from blade to blade and wheel to wheel. The result is leakage at the end of the air manifold between the blade or wheel and the cover plate normally installed to prevent such leakage. An end seal according to this invention reduces cooling air loss attributable to manufacturing tolerances between the blade base and the turbine wheel.